New Parameter in vehicle config

Hi all,
just for first testing, I like to add a new parameter moonhawk_transmission.jbeam and read it in the automaticGearbox.lua (in shiftlogic).
moonhawk_transmission.jbeam ("moonhawk_transmission_3A" :
"
"gearbox": {
"uiName":"Gearbox",
"gearRatios":[-2.18, 0, 2.46, 1.46, 1.00],
"parkLockTorque":2500,
"oneWayViscousCoef":40,
"friction": 1.65,
"dynamicFriction": 0.00167,
"torqueLossCoef": 0.017,
"gearboxNode:":["tra1"],
"bla": 1,

},"

automaticGearbox.lua:

(z324) local function determineTargetGearIndex()
.
.
.
log("I", "bla1", gearbox.bla ..dumps(bla1))
return gearIndex
(z364) end

If I load the moonhawk I get an error-message in the debug window. It seems that the parameter gearbox.bla does not exist.
I tried many other ways to make this run but I does not work.

Can somebody plaes tell me, what's my fault?

Thanks in advance!